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Anisotropy of Commercially Pure Titanium (CP-Ti)
Presenter: Madhav Baral
Advisor: Prof. Yannis P. Korkolis
Project Objective: To assess the anisotropy of Commercially Pure Titanium using extensive material testing
at various in-plane and through-thickness orientations with respect to rolling direction (RD) of a plate.
Motivation and Background
Experimental Setup and Procedures
Experimental Results
Results and Conclusions
Results: The load and displacement from the experiments can
be reduced to obtain stress and strain relationship as shown:
F
σE =
Ao
σT = σE (ԐE + 1
∆l
ԐE =
lo
ԐT = ln(ԐE + 1
True Stress-Strain Curves at orientations wrt to RD in plane strain
tension (PST) and plane strain compression (PSC)
Standard tension experiments using MTS and 3D DIC system
Titanium parts and components used in various commercial products
Motivation: Titanium has higher strength to weight ratio,
excellent corrosion resistance, and higher temperature
resistance than conventional steel alloys. Today, the need of
such material in the aerospace, nuclear, automobile, medical,
sports, and fashion industries is increasing. For example, the
strict CAFE regulation requires the auto manufacturers to
drastically increase the fuel efficiency of their vehicles in near
future. One of the promising ways to resolve this issue while
maintaining the safety standard is by using higher strength
and lighter weight materials like Titanium.
Introduction: Anisotropy in materials is induced due to
certain texture patterns that are produced during the
manufacturing process. This leads to inconsistency in
material properties in the rolling, transverse, and normal
directions.
CP-Ti Asymmetry in uniaxial tension-compression in RD, TD, and ND
Engineering Stress-Strain Curves at orientations wrt to RD in tension
CP-Ti Asymmetry in plane strain tension (PST)-compression (PSC)
in RD and TD
Tested tension specimens, Digital Image Correlation Images and
Infra-red thermal Images of specimens
True Stress-Strain Curves at orientations wrt to RD in compression
Layout of CP-Ti specimens on a rolled plate
with respect to the rolling direction
Objective: To assess (quantify) the anisotropy of CP-Ti using
Uniaxial and Plane Strain Tension and Compression tests at
different orientations with respect to RD. To generate enough
experimental data points (stress tensors) at different
deformation levels in order to calibrate an appropriate yield
function that can be implemented in commercial Finite
Element Analysis (FEA) packages to model the material.
Yield Surface and Plastic Work Contour predicted with von-Mises
Yield Criteria revealing a need for an appropriate yield function
Uniaxial compression and plane strain compression specimens
Flow Stress evolution in Tension and Compression
revealing Anisotropy and Asymmetry
University of New Hampshire, Department of Mechanical Engineering
Presented at the Annual Graduate Research Conference (GRC); April 14, 2015
Conclusions: The anisotropy and asymmetry of CP-Ti in
tension and compression is established by performing
different types of uniaxial, through-thickness, and plane strain
tension and compression tests at various orientations with
respect to rolling direction of a plate. The obtained results will
be used to calibrate an appropriate anisotropic yield function
that can be implemented in FEA for simulation and modeling
purposes.